T-Cell Therapy for Diffuse Interstitial Pontine Glioma

Laurence J.N. Cooper, M.D., Ph.D.

Funded in September, 2009: $200000 for 3 years

Can immune T cells that are engineered to target a deadly brain cancer in children lead to a cure?

Researchers will evaluate whether a new immune-based therapy for an incurable brain tumor that primarily occurs in children can be developed and effectively used in an animal model that resembles human cancers.

A lethal brain tumor, diffuse interstitial pontine glioma, occurs primarily in children. It is resistant to all currently marketed therapies and cannot be surgically removed because it is diffusely located within areas of the brainstem that are critical for maintaining life. One somewhat promising experimental approach to therapy involves using monoclonal antibodies to target a molecule, called “epidermal growth factor receptor” (EGFR) that resides on the surface of the glioma cells. Clinical trials of a monoclonal antibody, Nimotuzumab, which targets this receptor has demonstrated some therapeutic benefit in children with recurrent glioma, but was not curative. The investigators at MDACC, therefore, will explore whether this monoclonal antibody can be used to fashion T cells, a type of immune cell, so that they can be made into a weapon to fight this brain cancer. To explore this possibility, they will undertake research as part of an experimental therapeutic approach that is being tested in pet dogs suffering from a similar spontaneous brain tumor.

T cells have a native ability to kill cancer cells upon contact. Each T cell has a specialized receptor that is targeted to a specific protein on other cells, such that different T cells can sometimes target different tumors. The problem in developing T-cell therapy for pontine glioma is that naturally-ocurring T cells in children are unfortunately not capable of recognizing the glioma tumor cells. The investigators have developed a new technology to circumvent this problem by introducing into to T cells some of the genes that code for the Nimotuzumab monoclonal antibody coupled to areas of activity that can make a modified T cell specifically target EGFR, the receptor located on the glioma cells. They first will see whether this new technique effectively targets the similar brain tumors in the pet dogs. Through a collaboration with scientists at Texas A and M University, they have arranged for the pet dogs with spontaneously-occurring gliomas to receive their own T cells that have been engineered to specifically target canine EGFR on the glioma cells. Success would pave the experimental use of this technique in children with diffuse interstitial pontine glioma.

Significance: This new technique for engineering immune T cells to specifically target deadly diffuse interstitial pontine glioma cancer in children that may ultimately lead to a cure.

T-Cell Therapy for Diffuse Interstitial Pontine Glioma

This application seeks to evaluate whether we can generate and deploy a new immune-based therapy for a primary brain tumor that primarily occurs in children. Diffuse interstitial pontine glioma (DIPG) is a high grade pediatric brainstem glioma that has remained practically incurable for decades. To target DIPG, my laboratory has developed a chimeric antigen receptor (CAR) to redirect the specificity of T cells for epidermal growth factor receptor (EGFR) expressed on DIPG. This builds upon our technology to generate clinical-grade T cells that can be genetically modified to recognize CD19+ acute lymphoblastic leukemia independent of major histocompatibility complex (MHC) and despite the absence of T-cell costimulatory molecules on leukemic cells. One of the major hurdles to applying T-cell therapy to treat tumors has been the need to use vectors that integrates constitutive promoters and CAR transgenes into the T-cell genome. This raises the possibility of insertional mutagenesis and genotoxicity resulting in autonomous cell growth. Furthermore, stable expression of the CAR, while a benefit for long term immunosurveillance, may cause toxicity when the tumor antigen to be targeted, such as EGFR, is also expressed on normal cells. What is needed, and is provided here, is a new approach to cell and gene therapy that does not rely on integrating vectors to redirect the specificity of T cells with the proviso that multiple infusions of autologous T cells can be infused and re-infused with the expectation that transient expression of an EGFR-specific CAR on T cells can target DIPG and limit deleterious off-target effects. In Aim 1 we will develop and test a high throughput electroporation device for the non-viral introduction of in vitro transcribed mRNA expressing an EGFR-specific CAR. In preparation for a clinical trial in humans, we will assess our approach to redirecting T-cell specificity for immunotherapy of canine glioma. Therefore, this aim will use both human and canine T cells as a platform for electrotransfer. Recognizing that the expression of the EGFR-specific CAR from mRNA will be transient we will need sufficient T cells for repeated infusions. Thus to propagate T cells ex vivo, we will use artificial antigen presenting cells (aAPC) that have been pre-loaded with OKT3 (a murine monoclonal antibody (mAb) that binds the CD3 complex and activates T cells for proliferation) and which serve to efficiently numerically expand T cells. Recognizing that patients with DIPG chronically receive glucocorticoids, we will modify the aAPC culture conditions to propagate steroid-resistant T cells. The T cells that have undergone non-viral gene transfer will be assessed for their ability to specifically kill EGFR+ canine and human targets. Aim 2 will transition to the canine clinical trial. In collaboration with Texas A&M University, autologous T cells will be modified to express an EGFR-specific CAR from mRNA and repeatedly infused into pet dogs with spontaneous glioma. Feasibility for this project is enhanced by our approach to (i) efficiently propagate large numbers of human and canine T cells on g-irradiated aAPC, (ii) efficiently electroporate large numbers of T cells using our proprietary electroporation devices, (iii) express functional CAR from mRNA, and (iv) develop an EGFR-specific CAR from the scFv sequence derived from the EGFR-specific mAb Nimotuzumab, which is currently in clinical trials for DIPG. In aggregate, the data from these aims will establish whether serial infusions of EGFR-specific T cells, expressing CAR from introduced mRNA, can be used to treat canine glioma which lays the foundation for a human clinical trial to treat DIPG. The success of this grant application has implications not just for the treatment of DIPG, but for therapy using genetically modified T cells in general to treat other malignancies. The ability to generate tumor-specific T cells when they are needed, coupled with the reduced cost of nonviral gene transfer compared with viral transduction, will accelerate the ability of many investigators to deliver cell-based therapy for brain tumors as well as other malignancies in children and adults, alike.

Laurence J.N. Cooper, M.D., Ph.D.

Dr. Cooper is Chief of the Pediatric Cell Therapy Program at the University of Texas M.D. Anderson Cancer Center in Houston, Texas. His clinical practice focuses on caring for medically-fragile children with advanced malignancies to provide them with new therapies. While the children, adolescents, and young adults on his service undergo hematopoietic stem-cell transplantation (also referred to as "bone marrow transplants") some patients require additional therapeutic approaches to tackle relpased or refractory tumors. For, when a young person's cancer is resistant to conventional therapies, it may be susceptible to treatment with biologic therapies. Thus, Dr. Cooper and his team have developed a suite of investigational protocols to infuse immune cells, such as T cells and NK cells to treat solid tumors as well as cancers arising from the blood. To provide the science behind these clinical trials, Dr. Cooper supervises a large laboratory program that seeks to translate basic immunology into clinical practice. In this laboratory we are developing T cells that can attack pontine gliomas. These are an especially hard group of tumors to develop therapies for given the fact they grow in a child's brain stem. However, we have been able to genetically modify T cells so that they can attach to and then destroy tumor cells. The grant kindly provided by The Dana Foundation's Neuroimmunology program will enable us to further test whether our tumor-fighting T cells can be used to treat pontine glioma."

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